As technology continues to advance in data communications over a network, such as, for example, the Internet, the manner in which such a network is used continues to evolve. For example, the Internet has traditionally been used primarily for relatively low-bandwidth, latency-tolerant data traffic such as electronic mail (email) communications, document searching and retrieval. More recently however, as the bandwidth of network channels increases and as network data transmission rates increase, the Internet is being used to provide such services as multimedia streaming, Voice over Internet Protocol (VoIP), sometimes referred to as Internet calling, Internet Protocol television (IPTV), etc., which, due to the extensive bandwidth requirements of such services, had not previously been achievable using a network communication medium.
Network service providers (NSPs) find it highly desirable to be able to control certain types of data traffic being transmitted over their networks (e.g., VoIP traffic) so as to make it harder for consumers to use the Internet for phone calls or for swapping multimedia files. As stated in the article “Phone, Cable Firms Rein In Consumers' Internet Use,” by Peter Grant and Jesse Drucker, Wall Street Journal Online, pp. 1-4 (Oct. 21, 2005), which is incorporated by reference herein, these network service providers contend that such consumers are taking up too much space on networks and slowing down service for all customers that tap the Internet for email, video, music, phone and other services. Many network service providers stipulate in their subscription agreements that customers may not use the company's high-speed Web-access networks for Internet calling purposes. Several cable companies are using technology to cap the speed at which some of their customers are able to swap multimedia files (e.g., video).
Conventional solutions to the problem of controlling the flow of specific types of network traffic have, thus far, been unsuccessful or prohibitively expensive. Unfortunately, consumers have come to expect unfettered use of the Internet, and therefore any efforts by network service providers to control certain types of network traffic have been met with much resistance. One approach for controlling network traffic is for the network service provider to impose bandwidth limitations. This approach, however, is undesirable in that such bandwidth limitations applied to all types of network traffic can make a network service provider less competitive and, in addition, does very little to block VoIP traffic which is characteristically not high bandwidth. Another known approach is detecting specific traffic types using deep packet inspection (DPI) and then blocking or rate-limiting the specific traffic type detected. However, DPI only works for non-encrypted data traffic and it would be easy to defeat simply by having the VoIP traffic, or other traffic type, masquerade, for example, as Secure Sockets Layer (SSL) encrypted web traffic. Moreover, blocking specific types of data traffic may have certain legal implications for the network service provider which, in accordance with most service provider contracts, must typically guarantee a certain minimum bandwidth. Furthermore, rate-limiting will have little effect on VoIP traffic since, as previously explained, VoIP traffic is not bandwidth intensive.
Accordingly, there exists a need for improved techniques for detecting specific types of network traffic and for controlling the flow of such network traffic, which do not suffer from one or more of the problems exhibited by conventional network traffic detection and control methodologies.